Rick,
I'll bet that is the problem. There is a hose that is not visible without completely taking apart. If that is not it, call Polaris, they are great. They sent me a whole bunch of different replacement parts free of charge, including a PVC contraption to test the water pressure, guage not included. You hook it up to the end of the feeder hose. the pressure should be between 28-32 psi. Mine was exactly 29. So I knew that was not the problem, which led me down the road of complete disassembly. If you don't have adequate pressure at the end of the hose. Check at the wall next, to be sure it isn't something in the hose itself, like the back-up valve. Keep in mind the pressure will drop as the back-up valve kicks in.
Good Luck! Let me know how you make out.
Mark